JP3320596B2 - Piezoelectric / electrostrictive film element and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric / electrostrictive film element, especially an actuator, a filter, a display, a transformer, a microphone, a sound generator (such as a speaker), various oscillators, a resonator, an oscillator, and a discriminator. The present invention relates to a piezoelectric / electrostrictive film type element for generating or detecting a bending displacement or a force such as a unimorph type or a bimorph type used for a gyro or a sensor, and a method for manufacturing the same. is there. The element referred to herein means an element that converts electrical energy into mechanical energy, that is, an element that converts mechanical energy into mechanical displacement, force, or vibration, as well as an element that performs the reverse conversion. .

[0002]

BACKGROUND ART In recent years, in fields such as optics and precision processing,
Displacement elements that adjust the optical path length and position on the order of sub-microns, and detection elements that detect minute displacements as electrical changes, have been desired. In response to this, piezoelectric elements such as ferroelectrics have been required. Development of a piezoelectric / electrostrictive element used for an actuator or a sensor, which is an element utilizing the occurrence of displacement based on an inverse piezoelectric effect that occurs when an electric field is applied to a material or the opposite phenomenon, is being pursued. Among them, in a speaker or the like, a conventionally known unimorph type or the like is suitably used as such a piezoelectric / electrostrictive element structure.

[0003] For this reason, even the applicant of the present application, first,
JP-A-3-128681 and JP-A-5-49270
In the gazette, it can be suitably used for various applications,
A piezoelectric / electrostrictive film element made of ceramics was proposed. The previously proposed piezoelectric / electrostrictive film type element has at least one window (vacant space) and at least one thin wall by integrally providing a thin diaphragm so as to cover the window. A ceramic / substrate having a wall is formed, and a piezoelectric / electrostrictive operating portion comprising a combination of a lower electrode, a piezoelectric / electrostrictive layer and an upper electrode is formed on the outer surface of the diaphragm of the ceramic substrate. It is a small, inexpensive, highly reliable electromechanical transducer with a large displacement at a low driving voltage, and has a high response speed. It has excellent characteristics that it is fast and has a large generating force, and it has been recognized that it is truly useful as a constituent member of actuators, filters, displays, sensors, and the like. That.

However, as a result of further studies by the present inventors on such a piezoelectric / electrostrictive film element, such a piezoelectric / electrostrictive film element is located at a predetermined position of a diaphragm portion of a fired ceramic substrate. The lower electrode, the piezoelectric / electrostrictive layer, and the upper electrode constituting the piezoelectric / electrostrictive operating portion are sequentially laminated in layers by a film forming method, and are subjected to necessary heat treatment (firing) to obtain the piezoelectric / electrostrictive. Since the operating portion has a structure integrally provided on the diaphragm portion, the piezoelectric / electrostrictive operating portion, specifically, a heat treatment (firing) at the time of forming the piezoelectric / electrostrictive layer, It has been clarified that the piezoelectric / electrostrictive characteristics of such a piezoelectric / electrostrictive film type element are considerably reduced.

That is, by the heat treatment (firing) at the time of forming the piezoelectric / electrostrictive layer, the piezoelectric / electrostrictive layer (piezoelectric / electrostrictive operating portion) is fired between the piezoelectric / electrostrictive layer and the diaphragm portion of the ceramic substrate. The shrinkage causes stress, which hinders the sintering of such piezoelectric / electrostrictive layers, making it difficult to perform the sintering sufficiently, and the stress remains after firing. Therefore, there is a problem that the original characteristics of the piezoelectric / electrostrictive film type element cannot be obtained.

However, in order to improve the sinterability of such a piezoelectric / electrostrictive layer and to improve its compactness to improve the piezoelectric / electrostrictive characteristics of the piezoelectric / electrostrictive film type element, the piezoelectric / electrostrictive characteristics are improved.
Measures such as raising the firing temperature of the electrostrictive layer and reducing the thickness of the diaphragm on which the piezoelectric / electrostrictive layer is formed can be considered. However, the problem of residual stress after sintering cannot be solved, and the piezoelectric / electrostrictive characteristics, especially the driving of the piezoelectric / electrostrictive operating part, can be reduced by such residual stress. The problem that the amount of displacement of the diaphragm caused by the reduction of the diaphragm part or the resonance frequency of the element is low is still inherent, and further reducing the thickness of the diaphragm part also requires the production of the element. A new problem also arises that is difficult.

[0007] In the piezoelectric / electrostrictive film type element in which such stress is present, there is also a problem in the bonding between the diaphragm portion of the ceramic base and the piezoelectric / electrostrictive operating portion (lower electrode). In some cases, problems such as peeling may occur during the production and use of the device, which may lead to a decrease in the reliability of the device.

[0008]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a ceramic substrate made of a zirconia material, in other words, a thin zirconia substrate. On the outer surface of the diaphragm that constitutes the wall of
In the manufacture of a piezoelectric / electrostrictive film element formed by a film forming method, the effect of the diaphragm portion on the sinterability of the piezoelectric / electrostrictive layer is improved, and a piezoelectric material having a high sinterability (density) is improved. A manufacturing method capable of advantageously obtaining an element having high reliability and high conversion efficiency, which is formed as an electrostrictive layer and also effectively enhances the bonding between the diaphragm portion and the piezoelectric / electrostrictive operating portion;
And a piezoelectric / electrostrictive film element obtained by the method.

[0009]

A method for manufacturing a piezoelectric / electrostrictive film element according to the present invention is characterized by having at least one void and covering the void. A zirconia substrate integrally provided with a thin diaphragm portion, and a film composed of a lower electrode, a piezoelectric / electrostrictive layer, and an upper electrode which are sequentially provided in layers on the outer surface of the diaphragm portion by a film forming method. When manufacturing a piezoelectric / electrostrictive film-type element having a piezoelectric / electrostrictive operating portion having a shape, a fired calcined element containing at least the diaphragm portion containing 1.1 to 5.0% by weight of alumina is used. A zirconia substrate is prepared, and the lower electrode is formed on the outer surface of the diaphragm portion of the zirconia substrate by a film forming method, and then magnesia or the like is provided on the lower electrode. The above-mentioned piezoelectric / electrostrictive layer is formed by a film forming method using a piezoelectric / electrostrictive material containing the components independently or in the form of a compound, and sintering is carried out at least under the piezoelectric / electrostrictive layer. At the interface between the diaphragm and the lower electrode, particles mainly composed of a compound of alumina and magnesia are deposited.

In the method for manufacturing a piezoelectric / electrostrictive film element according to the present invention, the particles to be deposited are preferably spinel (MgAl ₂ O ₄ ) particles, and the piezoelectric / electrostrictive material For example, a material containing magnesia as one component of a composition exhibiting piezoelectric / electrostrictive characteristics is advantageously used. Furthermore, the effect of the present invention can be further enhanced by the fact that the diaphragm portion of the zirconia base has a shape that protrudes outward.

As described above, when the piezoelectric / electrostrictive layer is fired, a predetermined amount of alumina is allowed to exist in the diaphragm portion of the zirconia base while the piezoelectric / electrostrictive material constituting the piezoelectric / electrostrictive layer is included in the piezoelectric / electrostrictive material. , Magnesia or a component giving it, independently or in the form of a compound, such a component as magnesia migrates to the interface between the diaphragm portion and the lower electrode, and migrates through the diaphragm portion to the surface. Reacts with the alumina that has reached the temperature, and precipitates as particles of a compound such as spinel.During such sintering, the rigidity of the diaphragm decreases, or the diaphragm becomes plastic. The piezoelectric / electrostrictive layer can be advantageously densified, and the residual stress can be effectively eliminated or reduced. It is than a, it is the high piezoelectric / electrostrictive film type device reliability and displacement efficiency is obtained Te following. In addition, such a device has a feature that the resonance frequency does not decrease because the rigidity of the diaphragm does not decrease even after the piezoelectric / electrostrictive layer is fired. -ing

The present invention also provides a piezoelectric / electrostrictive film-type element which can be suitably manufactured according to the above-described method, and features of such a piezoelectric / electrostrictive film-type element. A zirconia base body having at least one cavity and a thin-walled diaphragm portion integrally provided so as to cover the cavity, and a layered film formed on the outer surface of the diaphragm portion by a film forming method. In a piezoelectric / electrostrictive film type device including a film-shaped piezoelectric / electrostrictive operating portion composed of a sequentially provided lower electrode, piezoelectric / electrostrictive layer, and upper electrode, at least a portion under the piezoelectric / electrostrictive layer Particles mainly composed of a compound of alumina and magnesia are present at an interface between the diaphragm and the lower electrode at an occupied area ratio of 5% or more.

In the piezoelectric / electrostrictive film type device according to the present invention, the compound of alumina and magnesia is preferably spinel (MgAl ₂ O ₄ ), such as spinel. Since the particles are interposed between the diaphragm portion and the lower electrode, the adhesion between the particles is effectively improved by the anchor effect of the particles.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the present invention relates to a film formed on a zirconia substrate by a film forming method on an outer surface of a diaphragm portion integrally formed so as to cover a space formed in the zirconia substrate. In a piezoelectric / electrostrictive film type element having a structure having a piezoelectric / electrostrictive operating portion, at least at an interface between a diaphragm portion located immediately below the piezoelectric / electrostrictive layer and a lower electrode,
It is intended to precipitate and make particles mainly composed of a compound of alumina and magnesia. An example of the basic structure of such a piezoelectric / electrostrictive film type element to which the present invention is applied is shown in FIG. It is shown in FIG. In addition, in the specific example illustrated here, the number of windows is one.

That is, in FIG. 1, a zirconia base 2 includes a base plate 4 having a rectangular window 6 of a predetermined size as a space and having a predetermined thickness as a support, and
It is formed integrally with a thin diaphragm plate 8 which is superimposed on one surface thereof and covers the window 6,
The portion of the diaphragm plate 8 located at the window 6 in the base plate 4 is a diaphragm portion 10. A film-like lower electrode 12, a piezoelectric / electrostrictive layer 14, and an upper electrode 16 are formed on the outer surface of the diaphragm portion 10 of the plate-like zirconia substrate 2, respectively.
Are sequentially laminated and formed as a film-shaped piezoelectric / electrostrictive operating portion 18 by a normal film forming method. As is well known, a predetermined voltage is applied to the lower electrode 12 and the upper electrode 16 through respective lead portions (not shown).

Therefore, in the piezoelectric / electrostrictive film type element having such a structure, when it functions as an actuator, the piezoelectric / electrostrictive film element is provided between the two electrodes 12 and 16 constituting the piezoelectric / electrostrictive operating portion 18. When an electric current is applied in the same manner as in the prior art and an electric field is applied to the piezoelectric / electrostrictive layer 14, an electric field-induced distortion based on such an electric field is induced. Thus, a bending displacement or force in a direction perpendicular to the plate surface of the zirconia base 2 (diaphragm portion 10) is developed.

According to the present invention, when manufacturing such a piezoelectric / electrostrictive film type device, first, at least the diaphragm portion 1 is formed.
0, a fired zirconia substrate 2 containing alumina in a ratio of 1.1 to 5.0% by weight is prepared. Then, the lower electrode 12 is placed on the outer surface of the diaphragm portion 10 of the zirconia substrate 2. After forming the film, the lower electrode 1
By using a piezoelectric / electrostrictive material containing magnesia or a component giving it independently or in the form of a compound on the piezoelectric / electrostrictive layer 14, a film is formed on the piezoelectric / electrostrictive layer 14 and then sintering is performed. The diaphragm portion 10 of the zirconia substrate 2 immediately below the piezoelectric / electrostrictive layer 14 and the piezoelectric / electrostrictive layer 14
Particles mainly composed of a compound of alumina and magnesia, such as spinel (MgAl ₂ O ₄ ), are deposited at the interface between the electrostriction operating portion 18 and the lower electrode 12. The stiffness of the diaphragm portion 10 during firing of the electrostrictive layer 14 is reduced, and the diaphragm portion 10 is easily plastically deformed, whereby the piezoelectric / electrostrictive layer 14 is effectively densified, and the piezoelectric / electrostrictive layer 14 is effectively densified. Residual stress due to firing shrinkage of No. 14 can also be effectively avoided.

In the piezoelectric / electrostrictive film type element which is the object of the present invention, as a material for providing the zirconia substrate 2 on which the piezoelectric / electrostrictive operating portion 18 is formed, various known stabilizing materials can be used. A zirconia material or a partially stabilized zirconia material can be appropriately selected and used. Among them, particularly, as disclosed by the present inventors in JP-A-5-270912, a compound such as yttria is added to form a crystal. The phase is mainly tetragonal, or mainly cubic, tetragonal, a mixed crystal consisting of at least two or more crystal phases of monoclinic, a material mainly composed of partially stabilized zirconia is preferable. used. Also,
The crystal grain size of such a zirconia substrate 2 is preferably 1 μm or less. The zirconia substrate 2 formed from such a material exhibits features such as high mechanical strength and high toughness even at a small thickness, and little chemical reaction with the piezoelectric / electrostrictive material. It is.

In the method of manufacturing a piezoelectric / electrostrictive film element according to the present invention, first, at least the diaphragm portion 10 of the zirconia substrate 2 made of such a zirconia material has a ratio of 1.1 to 5.0% by weight. A material containing alumina is prepared. Such inclusion of alumina is effective not only for the diaphragm portion 10 but also for other portions of the zirconia substrate 2, for example, the base plate 4 portion. However, if the content of alumina becomes too large, problems such as cracks and defects may occur in the diaphragm portion 10, so that the content is desirably 5.0% by weight or less, preferably 2.5% by weight or less. If the content is too small, the effect of the present invention cannot be sufficiently achieved, so that alumina must be contained in a proportion of at least 1.1% by weight or more.

Meanwhile, the zirconia substrate 2 having at least the diaphragm portion 10 containing a predetermined amount of alumina contains the predetermined amount of alumina at least in the portion where the diaphragm portion (10) of the green body for providing the zirconia substrate 10 is formed. The window portion 6 is obtained by producing a simulated product according to a known method and baking it, and in particular, employing a machining method such as a mold or ultrasonic processing. A thin zirconia green sheet provided with a predetermined amount of alumina and provided with a diaphragm plate 8 (diaphragm portion 10) is laminated on a zirconia green sheet provided with a hole and provided with a base plate 4 and thermocompressed. It is preferable to manufacture by integrating them from the viewpoint of high reliability. The piezoelectric / electrostrictive operating section 1 of such a zirconia base 2
The thickness at the diaphragm portion 10 where the 8 is formed is:
In order to obtain high-speed response and large displacement of the element, generally 5
It is desirable that the thickness be 0 μm or less, preferably 1 μm or more and 30 μm or less, and more preferably about 3 to 15 μm.

Each of the zirconia green sheets made of a predetermined zirconia material to provide the base plate 4 and the diaphragm plate 8 can be formed by laminating a plurality of sheet components.
Further, the diaphragm portion 10 in the zirconia substrate 2
In addition to the flat shape shown in FIG.
It is also possible to make the shape opposite to the outside, that is, a shape that is outwardly convex, or a shape that is recessed inward, in a state of being dropped into the window portion 6.
Can be more effectively achieved by using a zirconia substrate 2 having a shape that is convex outward (in FIG. 1, a shape that is convex upward). Here, the shape of the window 6 of the zirconia base 2, in other words, the shape of the diaphragm portion 10 is rectangular (square), but is not limited to this, and is not limited to this. Depending on the application of the mold element, for example, circular, polygonal, elliptical, etc.
Alternatively, an arbitrary shape, such as a shape obtained by combining these, and an arbitrary number and arrangement are appropriately selected.

Then, the fired zirconia base 2 prepared as described above is used, and its diaphragm portion 10
In order to form the target piezoelectric / electrostrictive operation section 18 on the upper side,
First, on the outer surface of the diaphragm portion 10, the lower electrode 12 is formed by using a predetermined electrode material in accordance with various known film forming techniques in the same manner as in the related art. Specifically, the electrode material that provides the lower electrode 12 is not particularly limited as long as it is a conductor that can withstand a high-temperature oxidizing atmosphere.
It may be an alloy, a mixture of an insulating ceramic such as bismuth oxide, zinc oxide or titanium oxide and a simple metal or an alloy thereof, or a conductive ceramic. However, more preferably, an electrode material mainly composed of a high melting point noble metal such as platinum, palladium, and rhodium, or an alloy such as silver-palladium, silver-platinum, and platinum-palladium, or platinum and a zirconia base material and / or Alternatively, a cermet material with a piezoelectric / electrostrictive material component is preferably used. Among them, more preferably, a material containing only platinum or a platinum-based alloy as a main component is preferable. The ratio of the zirconia base constituent material added to the electrode material is preferably about 5 to 30% by volume, and the ratio of the piezoelectric / electrostrictive material or its constituents is about 5 to 20% by volume. preferable.

The lower electrode 12 is formed by using such a conductive material to form a thick film by screen printing, spraying, coating, dipping, coating, or the like, or by sputtering, ion beam, vacuum deposition, ion plating, CVD, plating, or the like. In particular, the former thick film forming method is preferably adopted, and the lower electrode 12 formed by such a thick film forming method is preferably used. In general, the same heat treatment (firing) as in the prior art is performed for sintering of the electrode itself and further for integral bonding to the diaphragm portion 10. In addition, the thickness of the lower electrode 12 is generally 20 μm or less, preferably 5 μm or less.

Next, on the lower electrode 12 thus formed, a piezoelectric / electrostrictive layer 14 is further formed using a predetermined piezoelectric / electrostrictive material in accordance with various known film forming techniques. In this case, the above-described thick film forming method, specifically, the film forming method by screen printing, spraying, coating, dipping, coating, or the like is suitably adopted. If this thick film forming technique is used, the average particle diameter is about 0.01 μm to about 7 μm, preferably 0.05 μm.
The piezoelectric / electrostrictive layer 1 is formed on the outer surface of the diaphragm portion 10 of the zirconia substrate 2 by using a paste or a slurry mainly containing piezoelectric / electrostrictive ceramic particles of about 5 μm to 5 μm.
4 can be formed into a film, and good device characteristics can be obtained. Among these thick film forming methods, a screen printing method is particularly preferably used in that fine patterning can be formed at low cost. The thickness of the formed piezoelectric / electrostrictive layer 14 is preferably 50 μm or less in order to obtain a large displacement or the like at a low operating voltage.
More preferably, it is more preferably 3 μm or more and 40 μm or less.

In the present invention, as the piezoelectric / electrostrictive material for forming such a piezoelectric / electrostrictive layer 14, one containing magnesia or a component giving it independently or in the form of a compound. Is used. Here, the component that gives magnesia means a component that becomes magnesia in a later firing step or the like, such as magnesium alone. Specific examples of such a magnesia or a piezoelectric / electrostrictive material containing the component providing the magnesia include lead zirconate titanate (PZT).
Material), lead nickel niobate (PNN)
Material), a material mainly containing lead manganese niobate, a material mainly containing lead antimony stannate,
Magnesia, magnesium, etc. are added to a material mainly composed of lead zinc niobate, a material mainly composed of lead titanate, a material mainly composed of lead nickel tantalate, and a composite material thereof. In other words, there can be mentioned materials added and contained independently of the components of the piezoelectric / electrostrictive composition. In the present invention, the piezoelectric / electrostrictive characteristics are advantageously reduced. In the piezoelectric / electrostrictive composition shown, one containing magnesia in a compound form is used.
A material containing lead magnesium niobate (PMN) as a main component, a material containing lead magnesium tantalate as a main component, and a composite material of such a material and the above-described PZT-based material are preferably used. .

Further, among these piezoelectric / electrostrictive materials,
Material mainly composed of lead magnesium niobate, lead zirconate and lead titanate, and material mainly composed of lead nickel niobate, lead magnesium niobate, lead zirconate and lead titanate A material mainly composed of components of lead magnesium niobate, lead nickel tantalate, lead zirconate and lead titanate, or composed of lead magnesium tantalate, lead magnesium niobate, lead zirconate and lead titanate Materials based on components are advantageously used, and further, such materials include lanthanum, barium, niobium, magnesium, zinc, cerium, cadmium, chromium, cobalt, antimony, iron,
Oxides such as yttrium, tantalum, tungsten, nickel, manganese, lithium, strontium, and bismuth, and materials containing other compounds as additives are also preferably used.

In the case of such a multi-component piezoelectric / electrostrictive material, the piezoelectric / electrostrictive characteristics change depending on the component composition. However, lead magnesium niobate-zirconate preferably employed in the present invention. Ternary material of lead-lead titanate, lead magnesium niobate-lead nickel tantalate-
In the quaternary material of lead zirconate-lead titanate and lead magnesium tantalate-lead magnesium niobate-lead zirconate-lead titanate, the composition near the phase boundary of pseudo-cubic-tetragonal-rhombohedral Preferred, especially lead magnesium niobate: 15 to 50 mol%, lead zirconate: 10 to 4
5 mol%, lead titanate: 30 to 45 mol%, lead magnesium niobate: 15 to 50 mol%, lead nickel tantalate: 10 to 40 mol%, lead zirconate: 10 to 10 mol%
45 mol%, lead titanate: 30 to 45 mol%, furthermore, lead magnesium niobate: 15 to 50 mol%, lead magnesium tantalate: 10 to 40 mol%, lead zirconate: 10 to 45 mol%, Lead titanate: 30 to 45 mol%
Is advantageously employed because of its high piezoelectric constant and electromechanical coupling coefficient.

The content of magnesia in the piezoelectric / electrostrictive material or a component providing the same is contained in a compound form and constitutes one component of the piezoelectric / electrostrictive composition. Is used in such a piezoelectric / electrostrictive composition as it is, and when contained in an independent form, adversely affects the piezoelectric / electrostrictive characteristics of the formed piezoelectric / electrostrictive layer 14. Depending on the amount of alumina (1.1 to 5.0% by weight) contained in the diaphragm portion 10 at a ratio that does not bring about, it is appropriately determined at a ratio sufficient to be able to react with it to form a compound. It will be.

The piezoelectric / electrostrictive layer 14 formed on the lower electrode 12 as described above is subjected to a predetermined heat treatment (sintering) operation to form an integrated layer structure.
It is integrally joined on the diaphragm part 10.
The heat treatment (firing) temperature at this time is generally
Temperatures of the order of 500 ° C. to 1400 ° C. are employed, preferably temperatures in the range of 1000 ° C. to 1400 ° C. are advantageously chosen. In the heat treatment (firing) of the piezoelectric / electrostrictive layer 14 having such a film shape, the evaporation source of such a piezoelectric / electrostrictive material is used together with the evaporation source of the piezoelectric / electrostrictive material so that the composition of the piezoelectric / electrostrictive layer does not become unstable at a high temperature. In addition to heat treatment (firing) while controlling the atmosphere, a suitable cover member is placed on the piezoelectric / electrostrictive layer 14 so that the surface of the piezoelectric / electrostrictive layer 14 is directly exposed to the firing atmosphere. It is also recommended to adopt a firing method so as not to be exposed. In this case, a material similar to the zirconia base 2 is used as the cover member.

Further, by such a heat treatment (firing) of the piezoelectric / electrostrictive layer 14, the piezoelectric / electrostrictive layer 14 is sintered and densified, and has a desired piezoelectric / electrostrictive characteristic. It is also said that such heat treatment (firing)
By operation, the magnesia or its providing component present in the piezoelectric / electrostrictive layer 14 is allowed to move through the lower electrode 12 to the diaphragm portion 10 side of the zirconia substrate 2, and such Along with the movement, the alumina present in at least the diaphragm portion 10 of the zirconia base 2 also becomes lower electrode 1
2 and at least at the interface between the diaphragm portion 10 and the lower electrode 12 located immediately below the piezoelectric / electrostrictive layer 14, the moved alumina component and the magnesia component react to form particles of a predetermined compound. It precipitates and becomes present at such an interface.

The behavior of the alumina component during the calcination causes the rigidity of the diaphragm portion 10 of the zirconia base 2 to decrease, and the diaphragm portion 10 is easily plastically deformed.
Even if the piezoelectric / electrostrictive layer 14 is shrunk by firing, the generation of stress based on the shrinkage can be effectively avoided, whereby the densification of the piezoelectric / electrostrictive layer 14 can be effectively realized. In addition, since the original characteristics of the piezoelectric / electrostrictive layer 14 are obtained from a place where no stress remains, a piezoelectric / electrostrictive film element having high reliability and high displacement efficiency can be obtained. Further, the alumina component existing in the diaphragm portion 10 of the zirconia substrate 2 moves to the surface thereof and forms a compound with the magnesia component, so that the alumina component is hardly contained in the diaphragm portion 10. However, even in this case, the rigidity of the diaphragm portion 10 does not substantially decrease, so that the mechanical strength and the resonance frequency do not decrease.

As described above, in the zirconia substrate 2 having the diaphragm portion 10 convex outwardly, which is preferably used in the present invention, the sintering operation of the piezoelectric / electrostrictive layer 14 is performed by the above-described operation. An outwardly convex shape generally changes to an inwardly concave shape.

Thereafter, the fired piezoelectric / electrostrictive layer 1
4, the upper electrode 1 constituting the piezoelectric / electrostrictive operation section 18
6 is formed according to various known film forming techniques in the same manner as the lower electrode 12 using the electrode material that provides the same, and among them, a screen printing method using a resinate or a thick film paste, Alternatively, sputtering, ion beam, vacuum deposition, ion plating, CVD,
It is desirable that the film be formed in accordance with a film forming technique such as plating. The thickness of the upper electrode 16 is generally 20 μm or less, preferably 5 μm or less. Note that such an upper electrode 16
In general, the total thickness of the piezoelectric / electrostrictive operating section 18 obtained by adding the thickness of the piezoelectric / electrostrictive layer 14 and the thickness of the lower electrode 12 to the thickness of the piezoelectric / electrostrictive layer 14 is 100 μm or less, preferably 50 μm or less. .

By the way, the thus obtained piezoelectric /
In the electrostrictive film element, at least the diaphragm portion 10 of the zirconia substrate 2 immediately below the piezoelectric / electrostrictive layer 14 is provided.
Particles mainly composed of a compound of alumina and magnesia, such as spinel (MgAl ₂ O ₄ ), precipitate and exist at the interface between the lower electrode 12 of the piezoelectric / electrostrictive operating section 18 and such an interface. The surface of the diaphragm portion 10 providing the interface has a significant feature in that such particles are present in an occupied area ratio of at least 5% or more.

FIG. 2 shows the piezoelectric / electrode formed as described above.
Using the electrostrictive film type element, the piezoelectric / electrostrictive operating portion 18 is peeled off and removed, and the outer surface of the exposed diaphragm portion 10 located immediately below the piezoelectric / electrostrictive layer 14 is observed with an electron microscope. (A sketch drawing of the surface) obtained by the reaction, in which the precipitated particles 20 mainly composed of a compound formed by the reaction between alumina and magnesia are shown.
Are finely distributed as a whole as shown as a black pattern, and the precipitated particles 20
Interposed between the diaphragm portion 10 and the lower electrode 12, each functioning as an anchor for them,
Thus, the adhesion or the bonding strength between them is effectively increased.

In measuring the area occupied by the alumina / magnesia compound particles 20 on the surface of the diaphragm portion 10, first, the zirconia substrate 2 is moved to the piezoelectric / electrostrictive operating portion 18 (the lower electrode 1).
2. The piezoelectric / electrostrictive layer 14 and the upper electrode 16) are dissolved or decomposed by an appropriate method, and are separated and removed. For example, when the lower electrode 12 is mainly composed of a metal material, aqua regia prepared by mixing commercially available concentrated hydrochloric acid and concentrated nitric acid at a volume ratio of 3: 1 is used. While maintaining the aqua regia at a temperature of 80 ° C., a piezoelectric / electrostrictive film type element is put therein, and the piezoelectric / electrostrictive operating portion 18 is dissolved or decomposed and removed.
In this case, the removal operation is facilitated by boiling. Then, with respect to the zirconia base body 2 from which the piezoelectric / electrostrictive operation section 18 has been removed, the diaphragm portion 10
Of the piezoelectric / electrostrictive layer 14,
Alumina-magnesia compound particles 20 present on the surface portion of the lower electrode 12 immediately below the electrostrictive layer 14 were formed,
The area occupied by such compound particles 20 is obtained by observation with an electron microscope or the like, and the occupied area ratio is calculated according to the following equation. Occupied area ratio (%) = (A / A ₀ ) × 100 (where A ₀ corresponds to the area where the piezoelectric / electrostrictive layer 14 is formed, and the lower electrode 12 is formed immediately below the piezoelectric / electrostrictive layer 14). A is the area of the surface of the diaphragm portion 10 which has been removed, and A is the area of the surface of the diaphragm portion 10 from which the piezoelectric / electrostrictive operating portion 18 has been removed (corresponding to the area of the lower electrode 12 immediately below the piezoelectric / electrostrictive layer 14). ) Indicates the total area occupied by the alumina / magnesia compound particles 20.)

When the occupied area ratio of the particles 20 mainly composed of such a compound of alumina and magnesia is low, the effect of its existence cannot be sufficiently exhibited.
In the present invention, 5% or more, preferably 10% or more,
More desirably, it is 30% or more. The upper limit of the occupied area ratio is not particularly limited, but is preferably about 80% in view of problems such as cracks and defects.

The thus obtained piezoelectric / electrostrictive film type element according to the present invention does not suffer from a decrease in rigidity at the diaphragm portion, and therefore has no problem of lowering the resonance frequency. The piezoelectric / electrostrictive layer in the electrostriction operation section has a high density, and has a feature that the piezoelectric / electrostrictive layer has excellent reliability due to excellent piezoelectric / electrostrictive characteristics. It can be advantageously used for various applications such as. However, the piezoelectric / electrostrictive film type element according to the present invention has a piezoelectric / electrostrictive element provided on the outer surface side of the diaphragm portion.
Since the displacement and the force can be effectively performed by the operation of the electrostriction operation section, the actuator can be advantageously used as a piezoelectric / electrostriction actuator.
Various sensors such as filters, ultrasonic sensors, angular velocity sensors, acceleration sensors, and shock sensors, transformers, microphones, sound generators (such as speakers), discriminators, oscillators, oscillators, and resonators for power and communication, and others , Display and Kenji Uchino (Japan Industrial Technology Center)
Electrostrictive Actuators: From Basics to Applications ”(Morikita Publishing)
The element of the present invention is particularly advantageously used as a servo displacement element, a pulse drive motor, an ultrasonic motor, a unimorph type used for a piezoelectric fan, an actuator of a type that generates a bending displacement such as a bimorph type, or the like. What you get. Also, it can be suitably used as a thick film capacitor element.

FIG. 3 schematically shows an example of the piezoelectric / electrostrictive film type device according to the present invention, and FIG. 4 is an exploded perspective view thereof. The piezoelectric / electrostrictive film type device illustrated therein has a structure in which a zirconia base 22 and a piezoelectric / electrostrictive operating portion 24 disposed on the outer surface of the diaphragm portion thereof are integrated. The piezoelectric / electrostrictive operating section 24 bends and deforms the thin diaphragm portion of the zirconia base 22 according to the applied voltage.

More specifically, in the zirconia substrate 22, a closing plate (diaphragm plate) 26 and a connection plate (base plate) 28 each having a thin flat plate shape made of a predetermined zirconia material are also made of a predetermined zirconia material. Spacer plate (base plate)
It is integrally formed with the structure which overlapped on both sides of 30. The connection plate 28 has an opening 32 for communication. The number, shape, size, position, etc. of the communication opening 32 are determined by the piezoelectric /
It will be appropriately selected according to the use of the electrostrictive film element. In the spacer plate 30, a plurality (three in this case) of square windows 36 are formed. Then, for each of the windows 36, the connection plate 28
The spacer plate 30 is superimposed on the connection plate 28 so that each communication opening 32 provided in the connection plate 28 is opened. Furthermore, the connection plate 2 in this spacer plate 30
A closing plate 26 is overlapped on the surface on the side opposite to the side where 8 is overlapped, and the opening of the window 36 is covered with the closing plate 26. As a result, a pressurizing chamber 38 is formed inside the zirconia base 22 and communicates with the outside through the communication opening 32. As described above, such a zirconia base 22 is formed as an integrally fired product using a predetermined zirconia material. Also, here, the three-layer structure product including the closing plate (diaphragm plate), the spacer plate (base plate), and the connection plate (base plate) has been illustrated, but a four-layer structure product or a multi-layer structure product thereof or more is used. It is also possible.

The zirconia base 22 has a film-shaped piezoelectric / electrostrictive operating portion 2 at a position corresponding to each pressurizing chamber 38 on the outer surface of the closing plate 26.
4 are provided. The piezoelectric / electrostrictive operating portion 24 is formed by forming a lower electrode 40, a piezoelectric / electrostrictive layer 42, and an upper electrode 44 on the closing plate 26 located at the window 36 of the zirconia base 22, that is, on the outer surface of the diaphragm. It is formed by forming sequentially by a forming method. Therefore, in this piezoelectric / electrostrictive film type element, the inside of the pressurizing chamber 38 is pressurized based on the operation of the piezoelectric / electrostrictive operating section 24, and the pressurizing chamber 38
The discharge of the fluid inside can be effectively realized. Further, the piezoelectric / electrostrictive film type element having this structure can be used not only as an actuator but also as a sensor by extracting the bending displacement of the diaphragm as a voltage signal.

As described above, the piezoelectric / electrostrictive film type element having such a structure has at least its piezoelectric / electrostrictive layer 4.
2 Particles mainly composed of a compound of alumina and magnesia, such as spinel, are precipitated and present at the interface between the diaphragm portion (26) located immediately below and the lower electrode (40). 5% particle occupation area
The configuration is as described above. On the other hand, the upper electrode (4
The presence of particles mainly composed of a compound of alumina and magnesia, such as spinel, inside the piezoelectric / electrostrictive layer (42) sandwiched between 4) and the lower electrode (40) is a problem if the amount is small. However, there is a possibility of adversely affecting the piezoelectric / electrostrictive effect, which is not preferable.

[0043] Thus, the piezoelectric / electrostrictive membrane element of interest in the present invention, as described above, as an actuator or sensor or transformer inducer, advantageously speaker, display, servo displacement elements, pulse-driven motors , Ultrasonic motor, acceleration sensor, impact sensor, vibrator, oscillator, can be used for the constituent members of the resonator, but, of course, can be advantageously used in various other known applications, Needless to say.

[0044]

Hereinafter, typical examples of the present invention will be described to clarify the present invention more specifically. However, the present invention is not limited by the description of such examples. It goes without saying that it is not what you receive.
In addition, the present invention, in addition to the following examples, in addition to the specific description described above, unless departing from the spirit of the present invention, based on the knowledge of those skilled in the art, various changes,
It should be understood that modifications, improvements and the like can be made.

Example 1 In order to produce a piezoelectric / electrostrictive film type element as shown in FIGS. 3 and 4, a rectangular window 36 having a size of 0.3 mm × 0.5 mm was formed with a rectangular window 36 in the longitudinal direction of the substrate. 0.3m at intervals of .2mm
A fired zirconia substrate 22 having four different alumina contents as shown in Table 1 is prepared in the direction of the m side, and the alumina content is different from that shown in the following Table 1. On the outer surface of the diaphragm portion (26) of the zirconia substrate 22 Then, a lower electrode 40, a piezoelectric / electrostrictive layer 42, and an upper electrode 44 were sequentially formed as follows. The connection plate 28 constituting the zirconia base 22 is positioned at the center of the window 36 so that
A communication opening 32 having a diameter of 0.2 mm was provided.

When manufacturing such an element, the thickness of the connection plate 28 and the spacer plate 30 constituting the base portion (base plate) of the zirconia base 22 are each set to 150 μm after firing, and the diaphragm is formed. Diaphragm plate 26 for providing
Was 13 μm after firing. Further, as a material for providing the connection plate 28, the spacer plate 30, and the diaphragm plate 26, 3
Zirconia partially stabilized with mol% yttria was used. Then, in order to obtain the integrated zirconia base 22 by superimposing the diaphragm plate 26 on the connection plate 28 and the spacer plate 30, respective green sheets are produced as described below, and laminated and pressed. The firing was performed.

A) Preparation of Green Sheet for Diaphragm Plate 26 3 mol% yttria partially stabilized zirconia powder (average particle diameter 0.4 μm) (100-x) parts by weight Alumina powder (average particle diameter 0.2 μm) x parts by weight Polyvinyl butyral resin (binder) 9.0 parts by weight Dioctyl phthalate (plasticizer) 4.5 parts by weight Sorbitan fatty acid ester-based dispersant 2.0 parts by weight 70 parts by weight toluene / isopropyl alcohol (50/50) mixed solvent 70 parts by weight Was mixed in a pot mill using zirconia balls to obtain a slurry having an initial viscosity of 1200 cps (centipoise). Next, the slurry was vacuum-degassed and the viscosity was adjusted to 2000 cps, and then a green sheet was formed by a reverse roll coater to give a diaphragm portion having a thickness of 8 μm or 13 μm after firing. The drying was performed at 50 ° C. for 10 minutes.

B) Preparation of Green Sheet for Connection Plate 28 and Spacer Plate 30 3 mol% yttria partially stabilized zirconia powder (average particle diameter 0.4 μm) (100-x) parts by weight alumina powder (average particle diameter 0.2 μm) X parts by weight Polyvinyl butyral resin (binder) 8.0 parts by weight Dioctyl phthalate (plasticizer) 4.0 parts by weight Sorbitan fatty acid ester-based dispersant 1.0 part by weight Xylene / (n-) butyl alcohol (50/50) 63 parts by weight of mixed solvent The above composition was mixed in a pot mill using zirconia cobblestone to obtain a slurry having an initial viscosity of 2000 cps. Then, the slurry was vacuum defoamed and the viscosity was adjusted.
After setting to ps, a green sheet was formed by a doctor blade device so that the thickness after firing was 150 μm. The drying was performed at 80 ° C. for 2 hours.

The connection plate and the green sheet for the spacer plate obtained as described above are pattern-punched (formation of the communication opening 32 and formation of the window 36) by a predetermined die. And the green sheet for the diaphragm plate prepared above is superimposed on
Under a pressure of 0 kg / cm ² , thermocompression bonding was performed at 80 ° C. × 1 minute. Further, the obtained monolithic laminate was subjected to 150
Calcined at a temperature of 0 ° C. for 2 hours, and various zirconia substrates 2 having different alumina contents in the diaphragm portion and the substrate portion.
2 was obtained.

Next, a platinum paste is screen-printed at a predetermined position on the outer surface of the diaphragm portion (26) using the obtained various zirconia substrates 22 so that the thickness after firing becomes 3 μm. And dried at 120 ° C. for 10 minutes, and then baked at 1350 ° C. for 2 hours to form the lower electrode 40.

Further, thereafter, on the lower electrode 40,
The paste for forming a piezoelectric / electrostrictive layer is printed by screen printing so that the thickness after firing becomes 30 μm.
After drying at 0 ° C. for 20 minutes, the piezoelectric / electrostrictive layer 42 was formed by baking at 1275 ° C. for 2 hours. The piezoelectric / electrostrictive material includes a material composed of 38 mol% of lead magnesium niobate, 24 mol% of lead zirconate, and 38 mol% of lead titanate (a part of Pb is replaced by Sr and La). ) Powder (average particle size 0.9 μm),
A composition comprising 100 parts by weight of this powder, 3 parts by weight of an acrylic binder and 20 parts by weight of terpineol (solvent) is kneaded to obtain a paste having a viscosity of 100,000 cps, thereby preparing a paste for forming a piezoelectric / electrostrictive layer. did.
In firing the piezoelectric / electrostrictive layer 42, the piezoelectric / electrostrictive material powder used for preparing the piezoelectric / electrostrictive layer forming paste was present in a firing furnace, and the firing atmosphere was controlled.

After the sintering operation of the piezoelectric / electrostrictive layer 42 is completed, a Cr thin film is formed on the piezoelectric / electrostrictive layer 42 by a sputtering method, and a Cu film is further formed thereon. Thus, various target piezoelectric / electrostrictive film elements were obtained. Note that a voltage of 40 V is applied between the upper electrode 44 and the lower electrode 40 of each piezoelectric / electrostrictive operating portion 24 in the obtained piezoelectric / electrostrictive film type device so as to be in a forward direction with respect to the displacement direction. Over 10 minutes
Each was polarized.

The displacement characteristics and the resonance frequency of the various piezoelectric / electrostrictive film-type devices thus obtained were evaluated, and the piezoelectric / electrostrictive operation section 24 was removed to form the piezoelectric / electrostrictive layer 42. A portion of the diaphragm (26) where the lower electrode 40 is formed immediately below the piezoelectric / electrostrictive layer 42 is observed with an electron microscope, and the area occupied by particles mainly composed of a compound of alumina and magnesia deposited therebetween. Find the rate,
The results are shown in Table 1 below. Further, as a result of observation by such an electron microscope, it was confirmed that the precipitated particles were composed of spinel.

The displacement characteristics of the piezoelectric / electrostrictive film type element were evaluated by applying a voltage of 30 V in the same direction as the polarization treatment between the upper electrode 44 and the lower electrode 40 of each element.
Each of the piezoelectric / electrostrictive operating parts 2 by laser Doppler device
The measurement was performed by measuring the amount of displacement of No. 4 respectively. Regarding the occupied area ratio of the precipitated particles in each element, the aqua regia described above was used, and while keeping it at a temperature of 80 ° C., each element was turned on and each piezoelectric / electrostrictive operating section 24 was activated. After being dissolved or decomposed and removed, the diaphragm part (26) from which the piezoelectric / electrostrictive operating part 24 has been removed using an electron microscope provided with an elemental analysis function.
By observing the surface, the area occupied by the precipitated particles of each element was determined, and the occupied area ratio (%) was calculated according to the above-described equation.

[0055]

[Table 1] * Comparative example

As is apparent from the results shown in Table 1, the entire zirconia base 22 including the diaphragm portion (26) contains 1.1 to 5.0% by weight of alumina.
o. In the piezoelectric / electrostrictive film type devices of Nos. 3 to 6, the piezoelectric / electrostrictive material for forming the piezoelectric / electrostrictive layer 42 contains magnesia in a compound form. At the time of firing of 42, the magnesia component moves and reacts with the alumina component present in the diaphragm portion (26) at the interface between the diaphragm portion (26) and the lower electrode 40 (in this case, the connection plate 28 And some of the alumina components present in the spacer plate 30
(It has been recognized that it is involved in such a reaction) and produces spinel, which precipitates and is present at a high occupancy on the diaphragm surface. Yes, thereby realizing excellent displacement characteristics. Further, it is recognized that even if such an alumina component moves from the inside of the diaphragm portion (26) to the surface, the rigidity does not change, and therefore, the resonance frequency does not decrease.

On the other hand, when alumina is not sufficiently present in at least the diaphragm portion (26) of the zirconia substrate 22 constituting the piezoelectric / electrostrictive film element (No.
1 and 2) or in the case where they do not exist at all (Nos. 7 and 8), spinel particles do not sufficiently precipitate at the interface between the diaphragm portion (26) and the lower electrode 40, and do not precipitate at all. It is recognized that the effect of improving the displacement characteristics of the element is not sufficient.

Embodiment 2 In order to manufacture the piezoelectric / electrostrictive film type device shown in FIGS. 3 and 4, first, a rectangular window 36 having a size of 0.5 mm × 0.7 mm is formed in a rectangular shape. 0.2mm in the direction of 5mm side
A sintered zirconia base 22 having various alumina contents in the diaphragm portion (26), which are arranged in the longitudinal direction of the substrate at intervals of 10 (see FIG. 4), is prepared, and the diaphragm of the zirconia base 22 is prepared. The piezoelectric / electrostrictive operating part 24 was formed on the part (26) as follows.

Each green sheet providing each plate constituting the zirconia substrate 22 of the device was prepared as follows.

A) Preparation of Green Sheet for Connection Plate 28 and Spacer Plate 30 3 mol% yttria partially stabilized zirconia powder (average particle size 0.8 μm) 100 parts by weight Polyvinyl butyral resin (binder) 10 parts by weight dibutyl phthalate (plastic 5 parts by weight Sorbitan fatty acid ester dispersant 2 parts by weight Toluene / isopropyl alcohol (50/50) mixed solvent 73 parts by weight The above composition was mixed in a pot mill using zirconia balls to obtain a slurry having an initial viscosity of 1000 cps. . Next, the slurry was degassed in a vacuum and the viscosity was adjusted.
After the cps, the green sheet for the connection plate 28 and the green sheet for the spacer plate 30 were formed from the slurry by a doctor blade method so that the thickness after firing was 150 μm. The drying was performed at 80 ° C. for 3 hours.

B) Preparation of Green Sheet for Diaphragm Plate 26 3 mol% yttria partially stabilized zirconia powder (average particle diameter 0.8 μm) (100-x) parts by weight Alumina powder (average particle diameter 0.2 μm) x parts by weight Polyvinyl butyral resin (binder) 9 parts by weight Dibutyl phthalate (plasticizer) 4 parts by weight Sorbitan fatty acid ester-based dispersant 2 parts by weight Toluene / isopropyl alcohol (50/50) mixed solvent 70 parts by weight The above composition was prepared using zirconia cobblestone. Then, the mixture was mixed in a pot mill to obtain a slurry having an initial viscosity of 1000 cps. Then, the slurry was vacuum defoamed and the viscosity was adjusted.
After setting the pressure to ps, a green sheet was formed from the slurry using a reverse roll coater to give a diaphragm (26) having a thickness of 9 μm after firing.

The connection sheet green sheet and the spacer plate green sheet obtained as described above were pattern-punched (forming the communication opening 32 and the window 6) by using a predetermined mold. Thereafter, the green sheet for the diaphragm plate prepared above was superimposed on them, and at a pressure of 100 kg / cm ² at 80 ° C. × 1.
The thermocompression bonding was performed under the conditions of minutes. Then, the obtained integrated laminate was fired at a temperature of 1500 ° C. for 2 hours to obtain various zirconia substrates 22 having different alumina contents in the diaphragm portion (26). This results in Table 2 below.
No. shown in FIG. The zirconia substrates 22 of Nos. 9 to 12 had a shape in which the diaphragm portion (26) protruded outward (convex height: about 20 µm).

Next, using the obtained various zirconia substrates 22, a platinum paste is screen-printed at a predetermined position on the outer surface of the diaphragm portion (26) so that the thickness after firing is 5 μm. Print, 1 at 120 ° C
After drying for 0 minutes, the lower electrode 40 was formed by firing at 1350 ° C. for 2 hours.

Thereafter, a piezoelectric / electrostrictive layer 42 was formed on the lower electrode 40 as follows. The piezoelectric / electrostrictive material includes a material composed of 38 mol% of lead magnesium niobate, 24 mol% of lead zirconate, and 38 mol% of lead titanate (a part of Pb is replaced by Sr and La). The piezoelectric / electrostrictive layer forming paste prepared from the piezoelectric / electrostrictive material powder is screen-printed on the lower electrode 40 so that the thickness after firing becomes 30 μm. After printing and drying at 120 ° C. for 20 minutes, baking was performed by holding at 1275 ° C. for 2 hours. In such a firing operation, in the firing furnace,
The firing atmosphere was controlled in the presence of the piezoelectric / electrostrictive material powder.

After the sintering operation of the piezoelectric / electrostrictive layer 42 is completed, a Cr thin film is formed on the piezoelectric / electrostrictive layer 42 by a sputtering method, and a Cu film is further formed thereon. Thus, various target piezoelectric / electrostrictive film elements were obtained. In addition, a voltage of 100 V was applied between the upper electrode 44 and the lower electrode 40 of each piezoelectric / electrostrictive operating portion 24 in the obtained piezoelectric / electrostrictive film type element to perform a polarization process.

The displacement characteristics and resonance frequencies of the various piezoelectric / electrostrictive film elements thus obtained, and the occupation area ratio of spinel particles deposited on the interface between the diaphragm (26) and the lower electrode (40). Was evaluated in the same manner as in Example 1, and the results are shown in Table 2 below.

[0067]

[Table 2] * Comparative Example As is apparent from the results in Table 2, the diaphragm portion (26) was made to contain alumina in the amount specified in the present invention in accordance with the present invention. In the case of 10 to 12 elements, it is recognized that excellent displacement characteristics are exhibited.

[0068]

As is apparent from the above description, according to the present invention, at the time of firing the piezoelectric / electrostrictive layer, alumina contained in at least the diaphragm portion of the zirconia substrate and the piezoelectric / electrostrictive layer are formed. The magnesia component contained in the piezoelectric / electrostrictive material moves at least to the interface between the diaphragm portion directly below the piezoelectric / electrostrictive layer and the lower electrode, reacts there, and precipitates as particles of a compound composed of those components. As a result, the rigidity of the diaphragm during the firing of the piezoelectric / electrostrictive layer is effectively reduced, and the diaphragm is easily plastically deformed. Densification can be advantageously achieved, and residual stress due to firing shrinkage can be effectively avoided. As a result, a piezoelectric / electrostrictive film element having high displacement efficiency as well as reliability can be realized.

In the piezoelectric / electrostrictive film type element according to the present invention, the alumina component present inside the diaphragm moves to the surface by firing the piezoelectric / electrostrictive layer, Although the amount of alumina inside the diaphragm portion is remarkably reduced, the stiffness of the diaphragm portion hardly decreases after such firing, and therefore, the resonance frequency may be affected. There is no.

In the piezoelectric / electrostrictive film element according to the present invention, compound particles of alumina and magnesia are deposited at least at the interface between the diaphragm and the lower electrode immediately below the piezoelectric / electrostrictive layer. From the presence, such precipitated particles will function as an anchor to both the diaphragm portion and the lower electrode, so that the adhesion between the lower electrode and the diaphragm portion due to the anchor effect also increases It can be improved effectively.

[0071]

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing an example of a basic structure of a piezoelectric / electrostrictive film element according to the present invention.

FIG. 2 is an explanatory view showing the result of observing the surface of a diaphragm portion from which a piezoelectric / electrostrictive operating portion has been removed with an electron microscope.

FIG. 3 is a cross-sectional view showing another example of the piezoelectric / electrostrictive film type element to which the present invention is applied.

FIG. 4 is an exploded perspective view of the piezoelectric / electrostrictive film type device shown in FIG.

[Explanation of symbols]

 2, 22 Zirconia base 4 Base plate 6, 36 Window 8 Diaphragm plate 10 Diaphragm part 12, 40 Lower electrode 14, 42 Piezoelectric / electrostrictive layer 16, 44 Upper electrode 18, 24 Piezoelectric / electrostrictive operating part 20 Alumina / magnesia compound Particles 26 Closure plate 28 Connection plate 30 Spacer plate 32 Communication opening 38 Pressure chamber

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Nobuo Takahashi 2-56, Suda-cho, Mizuho-ku, Nagoya-shi, Aichi Japan Insulator Co., Ltd. (56) References JP-A-7-162048 (JP, A) (58) Surveyed fields (Int.Cl. ⁷ , DB name) H01L 41/09 H01L 41/22

Claims (5)

(57) [Claims] Claims: 1. There is at least one void,
A zirconia base body integrally provided with a thin-walled diaphragm portion so as to cover the space; a lower electrode, a piezoelectric / electrostrictive layer, and an upper electrode sequentially provided in layers by a film forming method on an outer surface of the diaphragm portion; When manufacturing a piezoelectric / electrostrictive film-type element having a film-shaped piezoelectric / electrostrictive operating portion composed of:
A fired zirconia base material containing 5.0% by weight is prepared, and the lower electrode is formed on the outer surface of a diaphragm portion of the zirconia base body by a film forming method. On the above, at least by forming the piezoelectric / electrostrictive layer by a film forming method using magnesia or a piezoelectric / electrostrictive material containing the component giving it independently or in a compound form, and performing firing, A method for producing a piezoelectric / electrostrictive film type element, comprising: depositing particles mainly composed of a compound of alumina and magnesia at an interface between the diaphragm and the lower electrode under the piezoelectric / electrostrictive layer. . 2. The method for manufacturing a piezoelectric / electrostrictive film element according to claim 1, wherein the particles to be deposited are spinel particles. 3. The method for manufacturing a piezoelectric / electrostrictive film type device according to claim 1, wherein the piezoelectric / electrostrictive material contains magnesia as one component of a composition exhibiting piezoelectric / electrostrictive characteristics. 4. Having at least one void,
A zirconia base body integrally provided with a thin-walled diaphragm portion so as to cover the space; a lower electrode, a piezoelectric / electrostrictive layer, and an upper electrode sequentially provided in layers by a film forming method on an outer surface of the diaphragm portion; A piezoelectric / electrostrictive film-type element comprising a film-shaped piezoelectric / electrostrictive operating portion comprising: a piezoelectric / electrostrictive film type element comprising at least an alumina at an interface between the diaphragm portion below the piezoelectric / electrostrictive layer and the lower electrode; A piezoelectric / electrostrictive film type element characterized in that particles mainly composed of a compound of magnesium and magnesia are present in an occupied area ratio of 5% or more. 5. The piezoelectric / electrostrictive film element according to claim 4, wherein the compound of alumina and magnesia is spinel.